Resolution studies on 5 GeV electron tracks observed with triple-GEM and MediPix2/TimePix-readout

This contribution investigates a prototype of a TPC readout with a highly pixelated CMOS ASIC, which is an option for charged particles tracking of the ILC. A triple GEM stack is joined with a TimePix and MediPix2 chip (pixel size of 55 × 55 μ m 2 ) and its readout properties are investigated with 5 GeV electrons. The spatial resolution of reconstructed cluster centers is determined as a function of the drift distance for different gases and stack configurations. Also the drift velocities are extracted. A single point resolution down to ≈ 25 μ m is achieved for small drift distances.